Device for controlling the electrical power supply of an oxygen pump of a linear oxygen probe
AssigneeSiemens Aktiengesellschaft
InventorPierre M. R. Metrich
Life of this patent
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Abstract
A device for controlling electrical power to an oxygen pump portion of a linear oxygen sensor comprises a bridge of transistors controlled by a microprocessor. The microprocessor processes a measurement signal delivered by a measurement cell of the probe in order to control the direction and duration of the passage through an oxygen pump of a current of predetermined strength, the current being controlled based on the measurement signal. The current is periodically alternated, and provided with a variable cyclic ratio, by appropriate switching of the transistors in the bridge. The device is used for the measurement of the air/fuel ratio in the mixture supplied to an internal combustion engine.
Claims11
A device for supplying electrical power to an oxygen pump of a linear oxygen probe for measuring oxygen concentration in exhaust gases from internal combustion engines, comprising:
- an oxygen pump of a linear oxygen probe including a pair of electrodes;
- a measurement cavity of the probe in communication with exhaust gases and with said oxygen pump;
- a measurement cell in communication with said measurement cavity, said measurement cell being sensitive to oxygen present in said measurement cavity of the probe to produce a corresponding measurement signal;
- an electrical power supply of the oxygen pump connected for control by the measurement signal, said power supply including:
- a source of electrical energy;
- and
- means for selectively connecting said source to said pair of electrodes of said oxygen pump so as to provide a current of alternating electrical strength of a fixed frequency and of variable cyclic ratio controlled by said measurement signal from said measurement cell, said fixed frequency being higher than a frequency of said measurement signal, said current being independent of oxygen concentration, said variable cyclic ratio being a measure of the oxygen concentration.
A power control circuit for controlling electrical energy from a voltage source, comprising:
- a linear oxygen probe having an oxygen pump, the oxygen pump being connected to receive electrical energy from the voltage source, the oxygen probe having an output producing a measurable signal;
- means for supplying a periodically alternating signal to said oxygen pump;
- and
- means for varying a cyclic ratio of said periodically alternating signal depending on a value of said measuring signal.
Dependencies are inferred from the claim text.